What Climate Is Ideal for Calla Lilies?

by Laura Reynolds

A white spathe shelters a yellow spadix that holds calla flowers.

Calla lilies (Zantedeschia spp.), also known as arum lilies, are not true lilies, but tender perennials that grow from tubers. They “bloom” on a finger-shaped organ, called a spadix, that is surrounded by an adapted leaf called a spathe. In the calla’s case, its spathe is particularly elegant. The plant grows best in conditions that mimic its native habitat.

Origins

Calla lilies hail from South Africa, where they grow from rhizomes in areas that are wetlands during the wet season and hot and dry during the long summers. Two groups of callas evolved from this mixed environment, white calla lily (Zantedeschia aethiopica) tolerates wet soils and grows in ditches along country roads. Other species tolerate full sun, heat and drought. Both groups grow in U.S. Department of Agriculture plant hardiness zones 9 through 10 and in USDA zone 8 with mulch. Callas bloom in early summer -- June and July in the Northern hemisphere. Some species of calla lily are considered invasive in some areas.

Adaptations

White calla lily is a familiar sight in dramatic arrangements for weddings and holidays, but Dutch hybridization has produced callas in a variety of rich colors, including yellow, red, maroon and peach. Hybrid callas grow from rhizomes, are deciduous and grow in part sun to full sun in USDA zone 8 to 10. Their wetland origins give callas a preference for organically rich soil, so rhizomes prosper in moist soil with a high humus content. In warmer areas, calla lilies are evergreen, but where winter temperatures drop below freezing, they are deciduous. The plants are damaged when temperatures fall below 25 degrees Fahrenheit.

Planting

Hybrid callas grow 10 to 24 inches tall and adapt easily to a sunny Mediterranean climate, with its warm summers and cool, wet winters. Plant rhizomes 2 inches deep in fall or spring. Space them at least 18 inches apart to allow room for the plants’ flamboyant foliage that may display spots, stripes or variegated greens. Large white callas may grow up to 3 feet long. If not grown in consistently moist soil, they might require watering during periods of drought.

Containers

Although calla lilies’ ideal climate is in USDA zones 9 though 11, they can grow as annuals in cooler regions. Plants lifted in fall can be kept in dry peat at 50 to 60 F and planted again in spring when nighttime temperature of the soil stays above 60 F. Callas also tolerate container growing in rich potting soil with good drainage. Containers should stay in a sheltered spot -- indoors in areas where winter temperatures fall below freezing -- to avoid waterlogged soil.

About the Author

An avid perennial gardener and old house owner, Laura Reynolds has had careers in teaching and juvenile justice. A retired municipal judgem Reynolds holds a degree in communications from Northern Illinois University. Her six children and stepchildren served as subjects of editorials during her tenure as a local newspaper editor.

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